Seven patients with Sweet's Syndrome (SS) accompanying leukaemia are presented. Six had acute myeloid leukaemia and one chronic myeloid leukaemia. SS developed during G-CSF therapy in two patients and following long periods of chemotherapy-associated neutropenia in two. This finding may suggest a possible role of G-CSF in the pathogenesis of SS. SS was diagnosed during the first presentation of three patients with leukaemia. Skin lesions on the lower extremiteies in two patients, widespread distribution in one, a local infiltration at the inguinal region and pleural effusion in one were interesting findings in our patients which are not usual for classical SS. (C) 1999 Elsevier Science Ltd. All rights reserved.